JP2014213560A - Method of producing resin molding and method of producing resin-made gear using the resin molding produced - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin molding having higher strength and a resin-made gear using the resin molding.SOLUTION: A method of producing a resin molding includes a first step of accumulating, by a papermaking method, a slurry prepared by mixing a short fiber, a powder resin and water to form an accumulated body of the short fiber and the powder resin, a second step of compressing the accumulated body in the thickness direction to form a molded raw material and a third step of pressure-molding the molded raw material while heating to form a resin molding. The short fiber has a protrusion part protruding outward in the fiber diameter direction and/or a concave part depressed inward in the fiber diameter direction on the peripheral surface. The ratio of the short fiber in the resin molding is preferably 5-85 vol.%.

Description

  The present invention relates to a method for producing a resin molded body and a method for producing a resin gear using the resin molded body produced thereby.

For automobiles and motorcycles, in order to respond to exhaust gas regulations and demands for improving fuel efficiency that are becoming stricter year by year, there is an increasing demand for lighter and smaller components. In order to meet such demands, it has been promoted to plasticize parts inside and around the engine.
In this flow, resin gears using high-strength and high-heat-resistant resins are used in the engine interior and the engine periphery as mating gears that mesh with metal gears. The resin gear contributes to weight reduction and suppression of noise at the time of meshing of teeth.

In particular, resin gears for automobile use are required to have high strength when used in the engine interior and the engine periphery.
Therefore, as described in Patent Documents 1 and 2, the resin gear uses a reinforcing fiber to achieve high strength retention by a composite of the reinforcing fiber and the resin.

JP 2009-154339 A JP 2009-154338 A

Resin gears for automobiles and motorcycles are required to be further reduced in weight and size when used inside and around the engine.
In order to meet such demands, it is necessary to further increase the strength of the resin gear material.

  The object of the present invention is made in view of the above problems, and is to manufacture a resin molded body having a higher strength and to manufacture a resin gear using the resin molded body.

In order to solve the above problems, the production method according to the present invention employs the following means.
According to a first aspect of the present invention, there is provided a first step in which a slurry prepared by mixing short fibers, a powdered resin, and water is accumulated by a papermaking method to form an aggregate of short fibers and a powdered resin, and the aggregate A method of manufacturing a resin molded body that undergoes a second step of forming a molding material by compressing the molding material in a thickness direction and a third step of forming a resin molding by heating and pressing the molding material. As the short fiber, a short fiber having a protruding portion protruding outward in the fiber radial direction and / or a concave portion recessed inward in the fiber radial direction is adopted as the short fiber.
A second invention is characterized in that, in the first invention, the fiber diameter of the short fibers is 0.005 to 3 mm, and the fiber length of the short fibers is 0.5 to 20 mm.
The third invention is characterized in that, in the first or second invention, the proportion of the short fibers in the resin molded body is 5 to 85% by volume.
The fourth invention is characterized in that, in the third invention, the short fibers include para-type wholly aromatic polyamide fibers and / or meta-type wholly aromatic polyamide fibers.
According to a fifth aspect of the present invention, there is provided a resin gear manufactured by obtaining a resin molded body by the manufacturing method according to any one of claims 1 to 4 and processing the resin molded body into a gear tooth portion. Is the law.

According to the method for producing a resin molded body of the present invention, the peripheral surface of the short fiber has a protruding portion protruding outward in the fiber radial direction and / or a concave portion recessed inward in the fiber radial direction. Entangling of short fibers is promoted, and a molding material that does not easily lose its shape is obtained. In this molding material, a powdery resin is held in a space formed by intertwining fibers. In the resin molded body produced by heat-press molding this molding material, the strength of the resin molded body is improved because the short fibers having a protruding portion and / or a recess are difficult to be pulled out from the resin molded body.
Moreover, the short fiber having a shape having a protruding portion and / or a concave portion causes a sufficient gap in the molding material formed by the entanglement of the short fibers. Therefore, when this molding material is heat-press molded, a resin molded body is produced in which the resin easily penetrates into the voids, and a portion where resin impregnation is insufficient (defective) is unlikely to occur.

  When the fiber diameter of the short fibers is 0.005 to 3 mm and the fiber length of the short fibers is 0.5 to 20 mm, the dispersibility of the fibers is improved when preparing a slurry for papermaking. Moreover, the strength of the produced resin molded body is further increased.

  When the proportion of the short fibers in the resin molded body is set to 5 to 85% by volume, a portion where the resin impregnation is insufficient (defect) is less likely to occur, and the strength of the manufactured resin molded body is further increased.

  When the short fiber includes a para-type wholly aromatic polyamide fiber and / or a meta-type wholly aromatic polyamide fiber, the reliability when the resin molded body is used in a high-temperature, high-load atmosphere becomes higher.

  Since it is as said effect, if a resin molding is obtained by said manufacturing method and this resin molding is processed into the tooth part of a gear, this resin gear will be a gear used for an automobile engine and its peripheral part. It is possible to maintain the strength and heat resistance required for the.

It is explanatory drawing which shows the shape of the short fiber used for the Example of this invention. It is explanatory drawing which shows the shape of the other short fiber used for the Example of this invention. It is explanatory drawing which shows the shape of the other short fiber used for the Example of this invention. It is a schematic cross section which shows the metal mold | die of the heat press molding used for the Example of this invention. It is a schematic cross section which shows the papermaking apparatus used for the Example of this invention. It is the schematic which shows the metal bushes used for the resin gears manufactured in the Example of this invention. The left figure shows a sectional view of a metal bush cut in the plane direction, and the right figure shows a sectional view cut in the same thickness direction. It is a schematic cross section which shows the fiber shape processing metal mold | die for obtaining the short fiber used for the Example of this invention. It is explanatory drawing which shows the shape of the short fiber used for the comparative example of this invention.

The resin used in the present invention is provided in a powder form (including a particle form), and various kinds of materials such as a thermosetting resin and a thermoplastic resin can be used. For example, epoxy resin, polyaminoamide resin, phenol resin, unsaturated polyester resin, polyimide resin, polyethersulfone resin, polyetheretherketone resin, polyamideimide resin, polyamide resin, polyester resin, polyphenylene sulfide resin, polyethylene resin, polypropylene A combination of one or more resins selected from resins can be used. Among these, a phenol resin is preferable from the viewpoints of the strength and heat resistance of the cured resin.
The particle shape of the powdery resin is arbitrary, but a granular resin is preferably used. Moreover, although a particle diameter changes with fiber diameters of a short fiber, 50 micrometers or less are preferable. Thereby, it can distribute uniformly in the gap | interval of the short fibers of the short fiber accumulation body. When the particle size is large, the fiber orientation of the short fiber aggregate may be disturbed, and when the resin molded body is manufactured by heat and pressure molding, the short fibers and the resin inside the resin molded body are not uniformly distributed. It can be a cause.

The short fibers used in the present invention are preferably selected from those having a melting point or decomposition temperature of 250 ° C. or higher. By using such short fibers, it is possible to produce a resin molded article having excellent heat resistance without causing thermal degradation of the short fibers at the molding temperature and processing temperature at the time of molding and the ambient temperature at the time of actual use. it can.
More specifically, what is preferably used as a short fiber is para-type wholly aromatic polyamide fiber, meta-type wholly aromatic polyamide fiber, carbon fiber, glass fiber, boron fiber, ceramic fiber, ultra-high strength polyethylene fiber , Polyketone fiber, polyparaphenylene benzobisoxazole fiber, wholly aromatic polyester fiber, polyimide fiber, and polyvinyl alcohol fiber can be used.
Among these, it is preferable to use para-type wholly aromatic polyamide fibers and / or meta-type wholly aromatic polyamide fibers from the viewpoint of the strength and heat resistance of the resin molded body.
Mixing and using para type wholly aromatic polyamide fiber, meta type wholly aromatic polyamide fiber, and fine fiber subjected to fibrillation is a particularly preferable mode, and high strength and heat resistance can be obtained.

  Although the fiber diameter of the short fiber used for this invention is not specifically limited, It is preferable to set it as 0.005-3 mm. As the fiber diameter becomes smaller, the strength of the fiber itself becomes weaker, and it becomes difficult to ensure the strength required for the resin molded body. When the fiber diameter is increased, the dispersibility of the short fibers decreases when preparing a slurry for papermaking. By setting the fiber diameter in the above range, the strength required for the resin molded product can be ensured more reliably, and the dispersibility of the short fibers becomes sufficient when preparing a slurry for papermaking.

Although the fiber length of the short fiber used for this invention is not specifically limited, It is preferable to set it as 0.5-20 mm. When the fiber length is shortened, the binding property (entanglement) between the short fibers becomes insufficient, and it becomes difficult to ensure the strength required for the resin molded body. When the fiber length becomes long, the dispersibility of the short fibers decreases when preparing a slurry for papermaking. By setting the fiber length in the above range, it is possible to ensure the strength required for the resin molded body, and the dispersibility of the fibers becomes sufficient when preparing a slurry for papermaking.
In addition, it is preferable that the fiber length of the short fiber is a dimension longer than the fiber diameter described above.
The fiber length is more preferably 3 to 14 mm, particularly from the balance between the strength of the resin molded body and the dispersibility during preparation of the papermaking slurry.

In the present invention, the protrusion protruding from the peripheral surface of the short fiber is not particularly limited as long as it protrudes radially outward from the peripheral surface of the short fiber, but the protrusion from the peripheral surface of the short fiber. When the height of the part is larger than 5% of the fiber diameter, the effect of ensuring the strength of the resin molded product and suppressing the decrease in resin impregnation deficiency (defect) is preferable.
The position of the protrusion is not particularly limited. For example, the peripheral surface excluding the end of the short fiber, the peripheral surface close to the end of the short fiber, and the end of the short fiber are torn. It can be the one spread out.
The protrusion can be formed as follows, for example.
When cutting a long fiber from a short fiber into a predetermined length, the end of the fiber is raised by using a cutting machine or the like whose blade edge has been worn in advance, and the protruding portion has a shape in which the end of the fiber branches off Can be formed (see FIG. 1A).
In addition, after cutting from long fibers into short fibers of a predetermined length, the ends of the fibers can be compressed by a press or the like or compressed (tapped) with a hammer or the like to form protrusions at the ends of the fibers. (See FIG. 1 (b)).

In the present invention, the recess recessed from the peripheral surface of the short fiber is not particularly limited as long as it is recessed radially inward from the peripheral surface of the short fiber, but the depth of the recess is larger than 5% of the fiber diameter. The effect of ensuring the strength of the resin molded body and suppressing the decrease in the impregnation (defect) of the resin impregnation is great.
The position of the concave portion is not particularly limited, but it is located farther from the end than the peripheral surface near the end of the short fiber, because it sufficiently entangles the fiber and makes it difficult to remove the short fiber from the resin molded body. It is preferable to provide it on the peripheral surface.
In addition, the protrusion part and recessed part which were mentioned previously can also be mixed. The method of mixing may be either using a short fiber having only a protruding portion and a short fiber having only a concave portion, or forming both a protruding portion and a concave portion in one short fiber. .
The recess can be formed as follows, for example.
By using a convex mold and compressing a part of the peripheral surface of the short fiber, it is possible to form a concave portion crushed on the side surface of the fiber. In this case, it is possible to form a projecting portion that is expanded by compression (see FIG. 2). The compression is preferably performed at an ambient temperature equal to or higher than the melting point of the short fiber.
Moreover, the surface of a short fiber can be damaged using a needle | hook, a cutter, etc., and a recessed part can be formed (refer FIG. 3).

  A slurry prepared by mixing the short fibers, the powdered resin, and water is made to form an aggregate of the short fibers and the powdered resin. Then, the aggregate is compressed in the thickness direction to form a molding material. The compression is performed until the aggregate of short fibers and powdered resin has a predetermined thickness. The compression time and temperature are arbitrary depending on the type of short fiber and powdered resin used. At the time of compression, a heater is attached to one opposing mold for compression and compression is performed in a heated state. May be. Thereby, the time which removes the water | moisture content contained in the shaping | molding raw material after papermaking can be shortened. Further, during the compression, by providing a through hole in the other opposing mold and compressing while sucking from the through hole, it is possible to shorten the time for removing moisture contained in the molding material after paper making.

  The concentration when the short fibers and the powdery resin are dispersed in water is preferably 0.3 g / liter or more and 20 g / liter or less. When fibers having a short fiber length are used, a slurry dispersed at a high concentration of 20 g / liter can be prepared because there is little entanglement between the fibers and good dispersion. On the other hand, when a fiber having a long fiber length is used, the fiber length is too long and cannot be sufficiently dispersed unless the concentration is as low as 0.3 g / liter.

  By the way, when the short fibers mentioned above contain fine fibers obtained by fibrillation of aramid fibers, the thickness dimension (axial dimension) of the short fiber and powder resin aggregate used when the diameter of the metal bush is 5 cm. Is about 10 cm. Then, by a compression operation to be described later, the aggregate of short fibers and powdered resin is compressed to about 2 cm and formed into a molding material.

  The resin molded body produced in the present invention is a composite of the short fibers and the resin described above, and is produced by heat-press molding the above-described molding material.

The heat and pressure molding can be performed using, for example, a mold as shown in FIG.
After the molding material is placed in a preheated mold, it is heated and pressed to cure the powdered resin, thereby molding a resin molded body. When the resin is cured, the resin molded body molded from the molding material is taken out from the mold to complete the production of the resin molded body.

Specifically, as shown in FIG. 4, after the molding structure 2 for the resin molding composed of the molding material 1 and the metal bush 6 is placed in the mold 3, the mold 3 is closed, The resin contained in the molding material 1 is cured by heating and pressing to form a resin molded body integrated with the metal bush 6.
The mold 3 includes a fixed mold 4, a movable mold 5 that is arranged at the center of the fixed mold 4 and is displaced in the vertical direction, and a metal bush 6 that is paired with the movable mold 5. An upper mold 7 is provided.

  When the pressing portion 7 </ b> A of the upper mold 7 is inserted into the fixed mold 4 and presses the metal bush 6, the moving mold 5 is displaced downward according to the amount of insertion of the upper mold 7. When the resin is cured, the resin molded body molded with the molding material 1 as a core material is taken out from the mold 3 to complete the production of the resin molded body.

  The ratio of the short fibers in the resin molded body is not particularly limited, but is preferably 5 to 85% by volume, and more preferably 30 to 60% by volume. If the proportion of short fibers decreases, the strength required for the resin molding cannot be secured. When the proportion of the short fibers increases, the resin melted at the time of heat and pressure molding does not flow to the entire resin molded body, and the occurrence rate of the resin impregnated portion increases. If the content of the short fibers is within the above range, the strength required for the resin molded product can be ensured, and the occurrence rate of insufficient resin impregnation (defective) can be reduced.

  In the resin gear manufactured in the present invention, the tooth portion is manufactured using the resin molded body described above. Specifically, when the resin molded body is manufactured, a metal is formed at the center portion thereof. A rotating shaft for rotating a gear is arranged at the center of a bush made of metal, and a resin molded body around the metal bush is cut with a tool such as a hob cutter or a shaving cutter to produce teeth.

Example 1
First, in order to produce a slurry, a tank filled with an amount of water that provides a concentration of short fibers and powdered resin at the time of charging of 4 g / liter is prepared. In this tank, the short fibers (para-type wholly aromatic polyamide fiber, meta-type wholly aromatic polyamide fiber, and fibrillated fine fiber are added so that the total amount of the short fibers in the resin molding becomes 40% by volume. Fiber) and a resin powder in an amount such that the total amount of resin in the resin molding is 60% by volume.
Specifically, the short fibers used in this example are para-type wholly aromatic polyamide fibers having an aspect ratio of 200, a single fiber fineness of 1.7 detex, and a fiber length of 3 mm (“Technora (registered trademark)” manufactured by Teijin Techno Products). )) 50% by mass, aspect ratio: 200, single fiber fineness: 2.2 detex, fiber length: 3 mm meta-type wholly aromatic polyamide fiber (Teijin Techno Products "Conex (registered trademark)") 45% by mass In addition, fine fibers ("Kevlar (registered trademark)" manufactured by DuPont Co., Ltd.) fibrillated to a freeness value of 300 ml are mixed in an amount of 5% by mass. In addition, phenol resin powder “Bellepearl (registered trademark)” manufactured by Air Water Bellpearl Co., Ltd. having a particle diameter of 20 μm is introduced as the powdery resin. Next, the water in the tank is stirred with a stirrer to disperse the fiber chop and the phenol resin powder.
The fiber end shape of the para-type wholly aromatic polyamide fiber (“Technola (registered trademark)” manufactured by Teijin Techno Products) and the meta-type wholly aromatic polyamide fiber (“Conex (registered trademark)” manufactured by Teijin Techno Products) are: As shown in FIG. 1 (a), when a cutting machine is used to cut a cutting blade from a long fiber to a short fiber using a cutting cutter in advance (polishing the blade edge). In addition, both ends of the short fiber are raised and protruded into a branched shape.

The metal bush 6 is positioned on the bush support 12 using the papermaking apparatus 8 shown in FIG.
In Example 1, the metal bush 6 shown in FIG. 6 is used, and each dimension is as follows. In addition, the protrusion part is made into the taper shape shape | molded by cutting.
・ Bush inner diameter: 30mm
・ Bush outer diameter: 50mm
・ Bush thickness: 13mm
・ Outer diameter of protruding part: 54mm
Then, as shown in FIG. 5B, the upper support 11 is moved downward, and the metal bush 6 is sandwiched between the bush support 12 and the upper support 11. Here, the position of the lower compression mold 14 was set such that the distance from the center in the axial direction of the metal bush 6 to the upper surface of the metal mesh 16 was 50 mm. In the papermaking apparatus 8, the papermaking slurry in which the short fibers and the resin powder described above are dispersed is charged. Then, vacuum suction is performed to drain water from the plurality of liquid passing pipes 15 provided in the lower compression mold 14, thereby separating the water in the papermaking slurry and obtaining the cylindrical accumulation body 17. In addition, in order to prevent short fibers from flowing out from the liquid flow pipe 15 during drainage, a 20 mesh mesh was used as the wire mesh 16.

Next, compression is performed in order to make the short fibers bite more firmly around the metal bush 6. As shown in FIG. 5C, the upper compression mold 13 is lowered to a position where the distance from the axial center of the metal bush 6 to the lower surface of the upper compression mold 13 is 50 mm. This position is a position where the metal bush 6 is located in the center between the lower compression mold 14 and the upper compression mold 13.
Then, as shown in FIG. 5D, the lower compression mold 14 and the upper compression mold 13 are placed with the metal bush 6 positioned at the center between the lower compression mold 14 and the upper compression mold 13. The fibers are moved toward each other at the same speed, and the fiber aggregates 17 are compressed until the thickness becomes 20 mm.
The molding material 1 integrated with the metal bush 6 was obtained by performing compression for 1 minute. During the compression, the compression is performed while continuously sucking vacuum from the liquid passage 15 of the lower compression mold 14.
The molding material 1 is dried until the moisture content becomes 0.5% by mass or less. Incidentally, in this embodiment, the thickness of the molding material 1 becomes 20 to 50 mm by the drying.

Next, as shown in FIG. 4, the molding structure 2 in which the molding material 1 and the metal bush 6 obtained in the above process are integrated is placed in a moving mold 5 heated to 200 ° C. Tighten. And the molding raw material 1 is heat-press-molded, a powdery resin is hardened, and a resin molding is obtained. If the resin is not sufficiently cured, a post-heating step may be applied as necessary to ensure that the resin is cured. Incidentally, in this embodiment, the molding material 1 having a thickness of 20 to 50 mm becomes 13 mm, which is substantially the same thickness as the metal bush 6 by the heat and pressure molding.
Teeth were formed by cutting on the outer periphery of the resin molded body to obtain resin gears having the dimensions shown in Table 1 below.

Example 2
Fig. 2 shows the fiber shapes of para-type wholly aromatic polyamide fibers ("Technola (registered trademark)" manufactured by Teijin Techno Products) and meta-type wholly aromatic polyamide fibers ("Conex (registered trademark)" manufactured by Teijin Techno Products). A resin gear was obtained in the same manner as in Example 1 except that the shape was as shown. That is, the short fiber was compressed by pressing, the thickness (height after crushing) was 95% or less of the fiber diameter, and the width widened by the compression was 105% or more of the fiber diameter. The process which provides a recessed part and a protrusion part to the surrounding surface of such a short fiber was implemented at the mold temperature of 270-300 degreeC using the metal mold | die with a convex shape as shown in FIG.

Example 3
Fig. 3 shows the fiber shapes of para-type wholly aromatic polyamide fibers ("Technola (registered trademark)" manufactured by Teijin Techno Products) and meta-type wholly aromatic polyamide fibers ("Conex (registered trademark)" manufactured by Teijin Techno Products). A resin gear was obtained in the same manner as in Example 1 except that the shape was as shown. That is, a concave shape having a depth of 1 to 25% of the fiber diameter was applied to the short fiber using a cutter such as a cutter knife in an atmosphere of 270 ° C. or higher.

Comparative Example 1
The fiber shapes of the para-type wholly aromatic polyamide fiber (“Technola (registered trademark)” manufactured by Teijin Techno Products) and the meta-type wholly aromatic polyamide fiber (“Conex (registered trademark)” manufactured by Teijin Techno Products) are shown in FIG. A resin gear was obtained in the same manner as in Example 1 except that the protruding portion as shown also had no recess and the peripheral surface was smooth.

<Resin gear durability evaluation>
Table 3 shows the durability evaluation results of the resin gears of Examples 1 to 3 and Comparative Example 1.
Durability evaluation was carried out using the two types of input torque (10 N · m, 20 N · m) shown in Table 2 below. The time required for the resin gear to continuously rotate at each input torque until the resin gear was destroyed was measured. Measured and confirmed durability.

  As shown in Table 3, in Examples 1 to 3, the durability was 300 hours or more at an input torque of 10 N · m, and 10 hours or more at an input torque of 20 N · m. , The durability does not increase, and the life at a particularly high input torque is deteriorated.

DESCRIPTION OF SYMBOLS 1 ... Molding material, 2 ... Molding structure, 3 ... Die, 4 ... Fixed mold, 5 ... Moving mold, 6 ... Metal bush, 7 ... Upper mold, 7A ... Pressing part, 8 ... Papermaking apparatus, DESCRIPTION OF SYMBOLS 10 ... Cylindrical metal mold, 11 ... Upper support stand, 12 ... Bush support stand, 13 ... Upper compression type, 14 ... Lower compression type, 15 ... Liquid-flow pipe, 16 ... Metal mesh, 17 ... Accumulation body

Claims (5)

A first step in which a slurry prepared by mixing short fibers, powdered resin and water is accumulated by a papermaking method to form an aggregate of short fibers and powdered resin;
A second step of compressing the aggregate in the thickness direction to form a molding material;
A method for producing a resin molded body that undergoes a third step of forming a resin molded body by heating and pressing the molding material,
As the short fiber, a short fiber having a protruding portion protruding outward in the fiber radial direction and / or a concave portion recessed inward in the fiber radial direction is adopted as the short fiber. Law.   The method for producing a resin molded body according to claim 1, wherein the short fibers have a fiber diameter of 0.005 to 3 mm and a fiber length of 0.5 to 20 mm.   The method for producing a resin molded product according to claim 1 or 2, wherein the proportion of short fibers in the resin molded product is 5 to 85% by volume.   The method for producing a resin molded product according to claim 3, wherein the short fibers include para-type wholly aromatic polyamide fibers and / or meta-type wholly aromatic polyamide fibers.   A method for producing a resin gear, comprising: obtaining a resin molded body by the manufacturing method according to any one of claims 1 to 4; and processing the resin molded body into a gear tooth portion.

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